$.fn.scrollTo = function(options) {
	var defaults = {
		toT: 0, //滚动目标位置
		durTime: 500, //过渡动画时间
		delay: 30, //定时器时间
		callback: null //回调函数
	};
	var opts = $.extend(defaults, options),
		timer = null,
		_this = this,
		curTop = _this.scrollTop(), //滚动条当前的位置
		subTop = opts.toT - curTop, //滚动条目标位置和当前位置的差值
		index = 0,
		dur = Math.round(opts.durTime / opts.delay),
		smoothScroll = function(t) {
			index++;
			var per = Math.round(subTop / dur);
			if (index >= dur) {
				_this.scrollTop(t);
				window.clearInterval(timer);
				if (opts.callback && typeof opts.callback == 'function') {
					opts.callback();
				}
				return;
			} else {
				_this.scrollTop(curTop + index * per);
			}
		};
	timer = window.setInterval(function() {
		smoothScroll(opts.toT);
	}, opts.delay);
	return _this;
};